A cement concrete pavement is configured to have a cement concrete slab resistant to shearing or bending generated from traffic loads to allow the stress caused by the load to be lowered than a supporting force of a lower course, thus maintaining structural stability. Generally, the cement concrete pavement includes a surface course and a subbase course, and the subbase course serves to supply equal supporting force to the slab, to previously prevent damages like pumping, and to provide safe working ground for casting concrete slab. The cement concrete pavements are generally classified into a jointed plane concrete pavement (JPCP), a jointed reinforced concrete pavement (JRCP), and a continuously reinforced concrete pavement (CRCP) in accordance with the reinforcement of the reinforced bar and joint spacing.
As shown in FIG. 1, the jointed plane concrete pavement is configured wherein there are no reinforced bars, except dowel bars or tie bars, and joints are equally spaced apart from each other, thus artificially controlling the positions of the occurrence of crack. If necessary, the dowel bars are arranged on the joints to help the transmission of load. In this case, no reinforcing bars exist on the entire portion except the joints in the jointed plane concrete pavement, and accordingly, the joints should be arranged to a given depth at appropriate timing so as to prevent crack from being generated from the entire portion except the joints.
The jointed plane concrete pavement causes riding quality to be deteriorated due to the breakage (stepped portions, corner crack, pumping, etc.) on the joints, so that longitudinal reinforcing steel bars are disposed on the center of the concrete slab, which is the jointed reinforced concrete pavement as shown in FIG. 2. The longitudinal reinforcing steel bars serve to prevent the crack generated due to the tensile force under the concrete slab from being excessively open. Accordingly, the jointed reinforced concrete pavement has the longer distance between the joints than the jointed plane concrete pavement, but still has the problem that structural breakage occurs on the joints and transverse crack portions.
As shown in FIG. 3, the continuously reinforced concrete pavement has a larger amount of longitudinal reinforcing steel bars than the jointed reinforced concrete pavement, thus completely removing the transverse joints. Since the continuously reinforced concrete pavement has no joints, it provides good riding quality and relatively long life span even under the heavy volume of traffic.
According to the conventional continuously reinforced concrete pavement, however, concrete is cast onto the reinforcing steel bars already arranged. As shown in FIG. 4, accordingly, the conventional continuously reinforced concrete pavement needs transverse reinforcing steel bars for supporting longitudinal reinforcing steel bars and spacers for supporting the transverse reinforcing steel bars so as to allow the longitudinal reinforcing steel bars to be located at the proper positions before concrete casting, thus undesirably increasing an amount of reinforcing steel bars consumed, requiring a large amount of labor due to manual operation, and reducing the whole construction speed.
Upon concrete casting, moreover, concrete is supplied just from the side of a road to be paved, so that it is hard to construct a pavement in small working space, such as, a concrete pavement into a tunnel, a tunnel entrance portion pavement, a bridge joint portion pavement, and a lane dividing section pavement, thus having many difficulties in domestic working environments.
According to the conventional continuously reinforced concrete pavement, further, the longitudinal reinforcing steel bars are overlappingly joined with each other, as shown in FIG. 5, so that a large amount of labor for the joining operation is consumed, and breakage on the road occurs well because the overlappingly joined portion and the concrete are not attached well to each other.